When does snow melt in Lappland?

I want to experience the seasonal change

Usually, when does sonw melt in Lappland (around Kiruna) and (around Harparanda) in spring? I know winter is very long in the north and it must accumlate thick snow on the ground. When temperature rise in spring, will this cause flooding as large amount of snow melting?

I wish to visit Lappland during the time it accumlates maximum snow, and see how they melt. Thanks!